Specifically, a dry corn fractionation system which operates to produce an endosperm fraction which can be concurrently of greater purity at greater yield than obtainable from corn milling or dry corn milling processes.
As shown in FIG. 1, certain conventional corn mill processes for ethanol production (1) may mill an amount of whole corn (2) into a mixture of corn particles (3)(referred to hereinafter as “milled corn”) which may include particles of corn bran, corn endosperm and corn germ. The milled corn (3) can be transferred to an ethanol production process (4) which includes the conventional steps of fermentation, distillation, and dehydration to generate an amount of ethanol (5). In the fermentation step, the milled corn (3) may be combined with an amount of water and an amount of alpha-amylase (or other enzyme capable of liquefying corn starch) to generate a mash in which the starch of the corn endosperm is liquefied. The mash may be held for a period of time at a temperature of between about 120 degrees Celsius (° C.) and about 150° C. to kill bacteria in the mash. The mash may then be held at a temperature of between about 90° C. and about 100° C. for a duration of time sufficient to achieve a desired level of liquefaction of the starch. An amount of gluco-amylase (or other enzyme capable of generating fermentable sugars from the liquefied starch) added to the mash converts the liquefied starch to fermentable sugars, such as dextrose, in a process referred to as saccharification. Yeast can then be added to the mash to convert the sugars to an amount of ethanol (5) and an amount of carbon dioxide (6) (or CO2) along with other volatile organics. The amount of carbon dioxide (6) can be stored or sold in the marketplace. For sale in to certain markets or for certain applications, the amount of carbon dioxide (6) can be stripped of the other volatile organics and captured as an amount of purified carbon dioxide (9). The fermented mash often referred to as “beer” comprises an amount of ethanol (5) in a concentration of about eight percent to about twenty percent by weight, other liquids and non-fermentable solids. The amount of ethanol (5) in the beer can be separated and concentrated to about 190 proof by conventional distillation techniques and dehydrated by application to molecular sieve to produce a dehydrated ethanol of about 200 proof. The about 200 proof ethanol may be combined with up to about five percent denaturant to generate an amount of fuel ethanol (10).
The stillage which remains after distillation of the beer can comprise an amount of liquid typically referred to as “thin stillage” and an amount of remaining solids typically referred to as the “distillers grains”. The thin stillage can be separated from the distillers grains (for example by centrifugation). The distillers grains can be dried by evaporation of the remaining thin stillage to produce “dried distillers grains” (“DDG”)(7). The thin stillage can be concentrated by evaporation of water to generate a syrup containing about thirty percent solids (also referred to as “condensed distiller soluble”). The syrup can be recombined with the dried distillers grains to generate an amount of distillers dried grain with solubles (8)(“DDGS”). The DDGS can be sold as animal feed.
Even though there is an increasing demand for fuel ethanol (10) worldwide and an increasing amount of research in ethanol production, there remain substantial unresolved problems with respect to conventional ethanol production.
A first substantial problem with conventional corn mill processes for ethanol production (1) can be that milled corn (3) introduced into the ethanol production process (4) which includes particles of corn bran, corn endosperm and corn germ requires an amount of thermal energy (11)(or energy Btus or Btus) to complete the steps of fermentation, distillation and dehydration, and by-product handling. To generate about a gallon of fuel ethanol (5), and a corresponding amount of DDGS (7) and carbon dioxide (6) the ethanol production process (4) utilizing milled corn (3) consumes an amount of thermal energy (11) of between about 30,000 and about 40,000 British thermal units (hereinafter “Btu”)(the term “about” as used herein means greater or lesser than the value or range of values stated by 10 percent, but not does not limit any value or range of values to this broader definition and each value or range of values preceded by the term “about” also includes in the alternative the stated absolute value or range of values). This amount of thermal energy (11) is typically generated by burning a corresponding amount of fossil fuel (12) such as oil, coal oil, coal or natural gas. Specifically, inclusion of an amount of non-fermentable biomass or biomass largely non-fermentable, such as corn bran or corn germ, into the ethanol production process requires allocation of an amount of thermal energy (11) to process the amount of non-fermentable biomass; however, this amount of non-fermentable biomass or biomass largely non-fermentable does not produce any or produces very little ethanol which increases the amount of thermal energy (11) per unit of ethanol (5) produced as compared to an ethanol production process in which only the fermentable corn endosperm is processed. Because the corn bran and corn germ represent about 15 percent by weight of the milled corn, if the corn bran and the corn germ can be removed from the ethanol production process, than the amount of thermal energy (11) consumed by the ethanol production process (4) could be substantially reduced.
A second substantial problem with the conventional corn mill process (1) for ethanol production can be that milled corn (3) introduced into the ethanol production process (4) which includes non-fermentable biomass or biomass largely non-fermentable requires allocation an amount of fermenter capacity to biomass which does not produce any or produces very little ethanol. If the corn bran and the corn germ can be removed from the ethanol production process, then the corresponding amount of fermenter capacity freed up could be utilized to process additional fermentable biomass.
A third substantial problem with the conventional corn mill process (1) for ethanol production can be that milled corn (3) introduced into the ethanol production process (4) which includes non-fermentable biomass or biomass largely non-fermentable increases the amount of “distillers grains” produced per unit of ethanol (5) produced. The distillers grains must be dried as above-described to produce dried distiller grains (“DDG”) (7) or dried distillers grains with solubles (“DDGS”)(8). The drying of “distillers grains” can be the single largest point of energy consumption in the ethanol production process (4). If the corn bran and the corn germ can be removed from the ethanol production process (5), then a corresponding reduction in the amount “distillers grains” can be achieved with a corresponding reduction in the amount of thermal energy (11) utilized to produce DDG per unit of ethanol (5) produced.
A fourth substantial problem with conventional corn mill processes for ethanol production can be that the market for conventional DDG (7) by products may become saturated as the number of ethanol production facilities increases. Conventional DDG (7) includes corn bran as the amount of corn bran is increased in the DDG (7) the percent protein by weight decreases. As the percent protein by weight of the DDG (7) decreases the value of the DDG (7) or DDGS (8) as a feed. Additionally, inclusion of corn bran in the DDG increase the fat content of the DDG which can make the DDG unacceptable as a feed for poultry and fish.
Now referring primarily to FIG. 2, an alternative to conventional corn mill processes (1) can be a dry corn mill process (13) which facilitates isolation of a corn bran fraction (15), a corn germ fraction (16), and a corn endosperm fraction (14). The corn endosperm fraction (14) generated from the conventional dry corn mill process (13) can be introduced into an ethanol production process (4) above-described to in part address certain of the above-identified problems. However, because the primary function of the conventional dry corn mill process (13) is to facilitate the production of a lowered-fat grit or meal for the production of food products such as cereal, table grits or the like, the conventional dry corn mill process (13) including hardware and methods of utilizing the hardware have not been optimized to provide a corn endosperm fraction (14) for introduction into an ethanol production process (4). As such, overall process yield of the corn endosperm fraction (14) useful in the ethanol production process (4) has never been the primary goal of the dry corn mill process (13) and as such corn endosperm recovery is typical sacrificed to increase corn endosperm purity. However, loss of corn endosperm in the context of an ethanol production process (4) solely to increase corn endosperm purity can result in significant economic losses.
To address the unresolved problems of conventional corn mill processes and conventional dry corn milling above-described the instant inventive dry corn fractionation system generates isolated corn fractions including a bran fraction, a germ fraction, and an endosperm fraction with high purity and at high yield which can be utilized independent of the other in proportioned recombination in the ethanol production process.